MARSUPIALS. 379 



and second incisor, and the outer or fifth incisor of the upper 

 jaw is separated from the rest by an interspace equal to twice its 

 own breadth, and moreover presents the triangular pointed canine- 

 like crown which characterizes all the incisors of Myrmecobius ; 

 but the four anterior incisors are placed close together, and have 

 compressed, quadrate, true incisive crowns. From these incisors 

 the canine is very remote, the interspace being equally divided by 

 the fifth pointed incisor, w^hich the canine very slightly exceeds in 

 size. In Per. nasuta the incisor presents the same general con- 

 dition, but the canines are relatively larger. In Per. Gunnii, the 

 outer incisor is closer to the others, which it also more nearly 

 resembles in form than in the preceding species ; but in Per. lagotis 

 (PL 98, fig. 5), it is not separated from the rest by a wilder interval 

 than that which intervenes between the first and second incisor. 

 In both the preceding Bandicoots the canines are long and well de- 

 veloped, but the true molars (m) have the grinding surface worn down 

 flat in the full-grown specimens which I have had the opportunity of 

 examining. 



Genus Cheer opus. — The singular animal on which Mr. Ogilby 

 has founded this genus differs from the true Perameles in having 

 but two toes on each fore-foot ; its dental formula is : 



Incisors — ; canines — : premolars -— ; molars — ; ^46. 



3 — 3 1 — 1 o — 3 4 — 4 



All the teeth are of small size ; the upper incisors are conical, 

 the lower ones truncated and the hindmost is notched ; the canines 

 are conical, compressed, the upper one simple and remote from 

 the incisors, the lower one near the incisors and notched anteriorly ; 

 the spurious molars are separated by intervals, as in Myrmecobius ; 

 they are tricuspid, except the first in the upper jaw which resembles 

 the canine. Each true molar consists of two triangular prisms, 

 those of the upper jaw being broader than those below, and with 

 their base turned outwards contrary to those in the lower jaw. 

 The genus would seem by its dentition to rank between Myrmecobius 

 and Perameles. Its digital characters are anomalous and unique 

 among the Marsupialia, but are evidently a degeneration from the 

 Saltatorial or Bandicoot type. 



